Abstract: Due to maturity of domestic oil and gas fields, Croatia is facing a problem of increasing demand that production cannot meet. Croatia is becoming more dependant on imported gas which is more expensive than domestic gas production. In order to decrease gas importing rates Croatian oil company INA started exploration of unconventional resurces. Together with Hungarian oil company MOL, INA has found few unconventional oil & gas reservoirs in Mura, Drava and Sava depression. Without of stimulation process like hydraulic fracturing it is almost impossible to exploit natural gas from this reservoirs because of very low permeability. Croatia is hoping to become unconventional gas producer because there is a lot of good examples of using unconventional gas to decrease domestic import rates and to increase natural gas supply security.